The subject matter disclosed in this application relates to a wave energy buoy.
Recent years have seen an increasing level of interest in methods of generating electrical energy without need for a continuous supply of fossil fuel. One of the methods currently of interest involves recovering energy from water waves using a wave energy buoy.
Referring to FIG. 1 of the drawings, one form of wave energy buoy comprises an elongate steel spar that carries a generally annular steel float. The spar is buoyant in sea water and is anchored to the sea bed at a height such that it penetrates the free surface of the water and, in calm conditions, extends substantially vertically upward.
The float is fitted about the spar and is supported relative to the spar for movement lengthwise of the spar by wheels (not shown) that are attached to the float and engage the exterior surface of the spar for guiding movement of the float. The spar and the float are provided with respective components of a linear generator. Thus, an armature is mounted internally of the spar and the float carries a permanent magnet assembly. As waves pass the spar, and the free surface of the water rises and falls relative to the spar, the float reciprocates lengthwise of the spar and electromagnetic interaction between the armature and the magnetic field of the permanent magnets generates an electromotive force that drives an electrical current in the armature. The armature is connected through cables (not shown) extending through the bottom end of the spar to collector cables leading to a shore-based distribution station.
The conventional wave energy buoy described above is subject to a number of disadvantages. First, the steel spar and float must be protected from corrosion by sea water, generally by painting. Any damage to the paint, for example by impact with flotsam, must be repaired promptly, which necessitates frequent inspection and maintenance. Painted steel structures are subject to build-up of deposits of aquatic organisms, which must be periodically removed to ensure that they do not interfere with movement of the float. For example, should a deposit cause one of the wheels supporting the float relative to the spar to jam or bind, movement of the float may result in the wheel scraping or gouging the surface of the spar. In addition, any sticking of the float relative to the spar reduces the electrical efficiency of the wave energy buoy.
Various forms of composite materials (including fiber reinforced plastic, or FRP) have been used for several years for manufacture of a wide range of industrial products. Techniques have been developed for manufacture of products of fairly complex shape using composite material. One method of forming an article of FRP involves winding strands of fiberglass around a core, which may be a collapsible mandrel, impregnating the fiberglass winding with resin, and curing the resin. Alternatively, an article of FRP may be fabricated by placing mats of glass fiber material against a mold surface, impregnating the glass fiber material with resin, and curing the resin. The curing may be effected either by baking at an elevated temperature of by catalysis at a lower temperature. The surface of the composite material may then be machined to a desired surface finish.
In certain applications of composite materials a silica carbide additive is included in the resin. Silica carbide is a hard material that renders the composite material resistant to damage by abrasion. For example, scrubbers used for removing sulphur dioxide from a coal/water slurry may include components made of composite material including silica carbide.